US Migatron Corporation Analog Ultrasonic Sensor
RPS-401A, RPS-426A analog ultrasonic sensors are housed in a cylindrical enclosure and are completely self-contained. Their supply voltage is 20-30 VDC and is protected against reverse polarity. They also have a narrow beam angle, allowing them to reach into sealed positions. A flat object can be tilted up to 8 degrees and still be detected.